Wrong number of arguments (0 for 1) in default scope - ruby-on-rails

Question

I keep getting the error ArgumentError: wrong number of arguments (0 for 1) for my default_scope which is default_scope { where("#{table_name}.tenant_id IS NULL") }
It keeps giving me this error and I don't understand why. I have the default scope in my users model.
Update:
Error output if using rails console:
ArgumentError: wrong number of arguments (0 for 1)
from /home/evan/Apps/demo-application/app/models/user.rb:18:in `hash'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/scoping.rb:64:in `value_for'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-4.0.4/lib/active_support/per_thread_registry.rb:40:in `public_send'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-4.0.4/lib/active_support/per_thread_registry.rb:40:in `block in method_missing'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/scoping/default.rb:123:in `ignore_default_scope?'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/scoping/default.rb:134:in `evaluate_default_scope'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/scoping/default.rb:110:in `build_default_scope'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/relation.rb:554:in `with_default_scope'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/relation.rb:582:in `exec_queries'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/relation.rb:471:in `load'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/relation.rb:220:in `to_a'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.0.4/lib/active_record/relation.rb:573:in `inspect'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/railties-4.0.4/lib/rails/commands/console.rb:90:in `start'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/railties-4.0.4/lib/rails/commands/console.rb:9:in `start'
from /home/evan/.rvm/gems/ruby-2.0.0-p195/gems/railties-4.0.4/lib/rails/commands.rb:62:in `<top (required)>'
from bin/rails:4:in `require'
The hash is in my user model as below.
def User.new_remember_token
SecureRandom.urlsafe_base64
end
def User.hash(token)
Digest::SHA1.hexdigest(token.to_s)
end
private
def create_remember_token
self.remember_token = User.hash(User.new_remember_token)
end
Error output if using rails server:
ArgumentError - wrong number of arguments (0 for 1):
activerecord (4.0.4) lib/active_record/scoping.rb:70:in `set_value_for'
activesupport (4.0.4) lib/active_support/per_thread_registry.rb:40:in `block in method_missing'
activerecord (4.0.4) lib/active_record/scoping/default.rb:127:in `ignore_default_scope='
activerecord (4.0.4) lib/active_record/scoping/default.rb:140:in `ensure in evaluate_default_scope'
activerecord (4.0.4) lib/active_record/scoping/default.rb:140:in `evaluate_default_scope'
activerecord (4.0.4) lib/active_record/scoping/default.rb:110:in `build_default_scope'
activerecord (4.0.4) lib/active_record/relation.rb:554:in `with_default_scope'
activerecord (4.0.4) lib/active_record/relation.rb:582:in `exec_queries'
activerecord (4.0.4) lib/active_record/relation.rb:471:in `load'
activerecord (4.0.4) lib/active_record/relation.rb:220:in `to_a'
activerecord (4.0.4) lib/active_record/relation/finder_methods.rb:316:in `find_take'
activerecord (4.0.4) lib/active_record/relation/finder_methods.rb:66:in `take'
activerecord (4.0.4) lib/active_record/relation/finder_methods.rb:49:in `find_by'
activerecord (4.0.4) lib/active_record/querying.rb:6:in `find_by'
app/helpers/sessions_helper.rb:16:in `current_user'
app/helpers/sessions_helper.rb:19:in `signed_in?'
And the relevant rails methods:
def ignore_default_scope? # :nodoc:
ScopeRegistry.value_for(:ignore_default_scope, self)
end
def ignore_default_scope=(ignore) # :nodoc:
ScopeRegistry.set_value_for(:ignore_default_scope, self, ignore)
end

Answer 1

You should avoid overwriting Ruby core methods like Object#hash, also considering that Object#hash is an essential method in Ruby. From the docs:
Generates a Fixnum hash value for this object. This function must have
the property that a.eql?(b) implies a.hash == b.hash.
The hash value is used along with eql? by the Hash class to determine
if two objects reference the same hash key. Any hash value that
exceeds the capacity of a Fixnum will be truncated before being used.
The hash value for an object may not be identical across invocations
or implementations of ruby. If you need a stable identifier across
ruby invocations and implementations you will need to generate one
with a custom method.
If you really have to overwrite core methods you should guarantee their functionality and do not change their arguments: you will get unexpected behaviours all over your app otherwise, like the error you're referring.

Answer 2

I think that you have not such a variable or method as table_name
I think this will work:
table name = "users"
default_scope { where("#{table_name}.tenant_id IS NULL") }
Also it is cleaner to use callable objects for scopes (they are waiting for it), so it is better to use lambda here:
table name = "users"
default_scope ->{ where("#{table_name}.tenant_id IS NULL") }
# or old syntax:
default_scope lambda { where("#{table_name}.tenant_id IS NULL") }